1. Field of the Invention
The present invention relates to a near-infrared absorbing and color compensation film composition for use in displays, such as plasma displays.
2. Description of the Related Technology
Plasma displays are self-emissive displays, and have advantages of large display area and small thickness. Because of these advantages, plasma displays have been used for large-screen televisions. In plasma displays, discharge gases generate ultraviolet (UV) rays to excite phosphors to emit light. During operation, considerable amounts of near-infrared rays are emitted from the plasma display.
A wavelength range of the near-infrared region overlaps with a wavelength band around 930 nm which is employed in many remote controllers used for household electronic devices. Accordingly, near-infrared rays generated from a plasma display may cause malfunctions or undesired operation in household electric appliances. Further, near-infrared rays generated from plasma displays may affect certain wavelength ranges of around 850 nm which are employed in infrared data communication. Accordingly, filters capable of efficiently blocking near-infrared rays in the range of 820 nm to 1,000 nm may be needed to block unwanted near-infrared rays emitted from plasma displays.
On the other hand, the color purity of red light emitted from phosphors of plasma displays drops considerably due to strong light emission in the vicinity of 590 nm. Due to the presence of neon gas, which is a major constituent of penning gases for exciting phosphors, orange neon light is always emitted at about 585 nm, regardless of colors generated from the phosphors. Accordingly, color compensation filters capable of selectively absorbing light in the range of 580 nm to 600 nm may be needed to reduce the emission of orange neon light and obtain more natural colors.
In addition to near-infrared blocking filters and color compensation filters, electromagnetic wave shielding filters are necessary to efficiently block large amounts of electromagnetic waves generated from plasma displays. Furthermore, since external light is strongly reflected in plasma displays, unlike in liquid crystal displays (LCDs), plasma displays have a problem of a low contrast ratio when used in bright environment. To solve this problem, it may be necessary to form an antireflective layer on the front surface of a display.
A front filter is configured to have near-infrared blocking, electromagnetic wave shielding, color compensation and antireflective functions. Such a front filter is prepared by laminating functional coating films, an adhesive layer, a protective film and a release film sequentially on a base film.
The release film and the protective film are removed after the lamination is completed. If more than one function of the films can be integrated in a single film, the amount of the release film and the protective film would be reduced. The adhesive layer is used to laminate the respective films. If the number of necessary films is decreased, the amount of the adhesive material will also be reduced. In addition, if the multiple functions are integrated in a single film, the base film may be omitted.
In this connection, many have attempted to decrease the number of films used to manufacture a filter for plasma displays. Methods for incorporating functional layers, e.g., a near-infrared absorbing layer and a color compensation layer, into an adhesive coating layer have been suggested as particularly promising methods.
For example, Japanese Patent No. 3621322 discloses infrared-absorbing sheets using a composition which comprises an infrared ray absorber having a maximum absorption wavelength at 700-1,100 nm. Japanese Patent Laid-open No. 2002-311843 discloses an electromagnetic wave shielding material using a composition which comprises an adhesive and an absorber capable of absorbing visible light and/or near-infrared rays. Japanese Patent Laid-open No. 2005-62506 discloses an optical film using a composition which comprises an adhesive and a near-infrared absorbing colorant having a maximum absorption wavelength at 800-1,100 nm.